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    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
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  <body>
    <script>
      // let this = window
      function fn() {
        // let this = window
        const obj = {
          age: 20,
          ref: this,
        };
        return obj;
      }

      const info = fn();
      console.log(info.ref);
      console.log(info.ref.age); // undefined
    </script>
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